Answers

If you look at the API Docs for the IApp interface and scroll down to the SwipeRightToLeft methods, you will see that there are 4 method overloads with the following signatures:

SwipeRightToLeft(Double, Int32, Boolean)
Performs a right to left swipe gesture.
SwipeRightToLeft(Func<Xamarin.UITest.Queries.AppQuery, Xamarin.UITest.Queries.AppQuery>, Double, Int32, Boolean)
Performs a right to left swipe gesture on an element matched by 'query'.
SwipeRightToLeft(Func<Xamarin.UITest.Queries.AppQuery, Xamarin.UITest.Queries.AppWebQuery>, Double, Int32, Boolean)
Performs a right to left swipe gesture on an element matched by 'query'.
SwipeRightToLeft(String, Double, Int32, Boolean)
Performs a right to left swipe gesture on the matching element. If multiple elements are matched, the first one will be used.

it thinks I'm trying to use one of the other SwipeRightToLeft signatures (that has a string as the first parameter)

error CS1660: Cannot convert lambda expression' to non-delegate type string'. I guess the lambda expression isn't cutting it. I'd just like to see a simple example somewhere of using an XPath to do the swipe.